ISO 18441:2016

INTERNATIONAL ISO
STANDARD 18441
Second edition
2016-11-15
Space data and information transfer
systems — Space link extension —
Application program interface for transfer
services — Core specification
Systèmes de transfert des informations et données spatiales — Extension de
liaisons spatiales — Interface du programme d'application pour les services
de transfert — Spécification de base
Reference number
ISO 18441:2016(E)
©
ISO 2016

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ISO 18441:2016(E)
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©  ISO 2016
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any
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ISO 18441:2016(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of
ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2. www.iso.org/directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent
rights identified during the development of the document will be in the Introduction and/or on the ISO list of
patent declarations received. www.iso.org/patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO's adherence to the WTO principles in the Technical Barriers to Trade (TBT)
see the following URL: Foreword - Supplementary information
ISO 18441 was prepared by the Consultative Committee for Space Data Systems (CCSDS) (as CCSDS
914.0-M-2, September 2015) and was adopted (without modifications except those stated in clause 2 of this
International Standard) by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 13, Space data and information transfer systems.
This second edition cancels and replaces the first edition (ISO 18441:2013), which has been technically
revised.
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ISO 18441:2016(E)
API FOR SLE TRANSFER SERVICES—CORE SPECIFICATION
STATEMENT OF INTENT
The Consultative Committee for Space Data Systems (CCSDS) is an organization officially
established by the management of its members. The Committee meets periodically to address
data systems problems that are common to all participants, and to formulate sound technical
solutions to these problems. Inasmuch as participation in the CCSDS is completely
voluntary, the results of Committee actions are termed Recommendations and are not in
themselves considered binding on any Agency.
CCSDS Recommendations take two forms: Recommended Standards that are prescriptive
and are the formal vehicles by which CCSDS Agencies create the standards that specify how
elements of their space mission support infrastructure shall operate and interoperate with
others; and Recommended Practices that are more descriptive in nature and are intended to
provide general guidance about how to approach a particular problem associated with space
mission support. This Recommended Practice is issued by, and represents the consensus of,
the CCSDS members. Endorsement of this Recommended Practice is entirely voluntary
and does not imply a commitment by any Agency or organization to implement its
recommendations in a prescriptive sense.
No later than five years from its date of issuance, this Recommended Practice will be
reviewed by the CCSDS to determine whether it should: (1) remain in effect without change;
(2) be changed to reflect the impact of new technologies, new requirements, or new
directions; or (3) be retired or canceled.
In those instances when a new version of a Recommended Practice is issued, existing
CCSDS-related member Practices and implementations are not negated or deemed to be non-
CCSDS compatible. It is the responsibility of each member to determine when such Practices
or implementations are to be modified. Each member is, however, strongly encouraged to
direct planning for its new Practices and implementations towards the later version of the
Recommended Practice.
CCSDS 914.0-M-2 Page ii September 2015
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ISO 18441:2016(E)
API FOR SLE TRANSFER SERVICES—CORE SPECIFICATION
FOREWORD
Attention is drawn to the possibility that some of the elements of this document may be the
subject of patent rights. CCSDS has processes for identifying patent issues and for securing
from the patent holder agreement that all licensing policies are reasonable and non-
discriminatory. However, CCSDS does not have a patent law staff, and CCSDS shall not be
held responsible for identifying any or all such patent rights.
Through the process of normal evolution, it is expected that expansion, deletion, or
modification of this document may occur. This Recommended Standard is therefore subject
to CCSDS document management and change control procedures, which are defined in
Organization and Processes for the Consultative Committee for Space Data Systems
(CCSDS A02.1-Y-4). Current versions of CCSDS documents are maintained at the CCSDS
Web site:
http://www.ccsds.org/
Questions relating to the contents or status of this document should be sent to the CCSDS
Secretariat at the e-mail address indicated on page i.
CCSDS 914.0-M-2 Page iii September 2015
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ISO 18441:2016(E)
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At time of publication, the active Member and Observer Agencies of the CCSDS were:
Member Agencies
– Agenzia Spaziale Italiana (ASI)/Italy.
– Canadian Space Agency (CSA)/Canada.
– Centre National d’Etudes Spatiales (CNES)/France.
– China National Space Administration (CNSA)/People’s Republic of China.
– Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Germany.
– European Space Agency (ESA)/Europe.
– Federal Space Agency (FSA)/Russian Federation.
– Instituto Nacional de Pesquisas Espaciais (INPE)/Brazil.
– Japan Aerospace Exploration Agency (JAXA)/Japan.
– National Aeronautics and Space Administration (NASA)/USA.
– UK Space Agency/United Kingdom.
Observer Agencies
– Austrian Space Agency (ASA)/Austria.
– Belgian Federal Science Policy Office (BFSPO)/Belgium.
– Central Research Institute of Machine Building (TsNIIMash)/Russian Federation.
– China Satellite Launch and Tracking Control General, Beijing Institute of Tracking and
Telecommunications Technology (CLTC/BITTT)/China.
– Chinese Academy of Sciences (CAS)/China.
– Chinese Academy of Space Technology (CAST)/China.
– Commonwealth Scientific and Industrial Research Organization (CSIRO)/Australia.
– Danish National Space Center (DNSC)/Denmark.
– Departamento de Ciência e Tecnologia Aeroespacial (DCTA)/Brazil.
– Electronics and Telecommunications Research Institute (ETRI)/Korea.
– European Organization for the Exploitation of Meteorological Satellites
(EUMETSAT)/Europe.
– European Telecommunications Satellite Organization (EUTELSAT)/Europe.
– Geo-Informatics and Space Technology Development Agency (GISTDA)/Thailand.
– Hellenic National Space Committee (HNSC)/Greece.
– Indian Space Research Organization (ISRO)/India.
– Institute of Space Research (IKI)/Russian Federation.
– KFKI Research Institute for Particle & Nuclear Physics (KFKI)/Hungary.
– Korea Aerospace Research Institute (KARI)/Korea.
– Ministry of Communications (MOC)/Israel.
– National Institute of Information and Communications Technology (NICT)/Japan.
– National Oceanic and Atmospheric Administration (NOAA)/USA.
– National Space Agency of the Republic of Kazakhstan (NSARK)/Kazakhstan.
– National Space Organization (NSPO)/Chinese Taipei.
– Naval Center for Space Technology (NCST)/USA.
– Scientific and Technological Research Council of Turkey (TUBITAK)/Turkey.
– South African National Space Agency (SANSA)/Republic of South Africa.
– Space and Upper Atmosphere Research Commission (SUPARCO)/Pakistan.
– Swedish Space Corporation (SSC)/Sweden.
– Swiss Space Office (SSO)/Switzerland.
– United States Geological Survey (USGS)/USA.
CCSDS 914.0-M-2 Page iv September 2015
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ISO 18441:2016(E)
API FOR SLE TRANSFER SERVICES—CORE SPECIFICATION
DOCUMENT CONTROL
Document Title Date Status
CCSDS Space Link Extension—Application October Original issue, superseded
914.0-M-1 Program Interface for Transfer 2008
Services—Core Specification,
Recommended Practice, Issue 1
CCSDS Space Link Extension—Application September Current issue:
– updates text to
914.0-M-2 Program Interface for Transfer 2015
accommodate
Services—Core Specification,
changes in current
Recommended Practice, Issue 2
versions of SLE
service specifications;
– differentiates
applicability by SLE
service specification
version;
– updates references.
NOTE – Substantive changes from the previous issue are marked with change bars in the
inside margin.
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ISO 18441:2016(E)
API FOR SLE TRANSFER SERVICES—CORE SPECIFICATION
CONTENTS
Section Page
1 INTRODUCTION. 1-1
1.1 PURPOSE OF THIS RECOMMENDED PRACTICE . 1-1
1.2 SCOPE . 1-1
1.3 APPLICABILITY . 1-2
1.4 RATIONALE. 1-3
1.5 DOCUMENT STRUCTURE . 1-4
1.6 DEFINITIONS. 1-7
1.7 REFERENCES . 1-10
2 DESCRIPTION OF THE SLE API . 2-1
2.1 INTRODUCTION . 2-1
2.2 SPECIFICATION METHOD AND NOTATION . 2-2
2.3 LOGICAL VIEW . 2-7
2.4 SECURITY ASPECTS OF CORE SLE API CAPABILITIES. 2-58
3 SPECIFICATION OF API COMPONENTS . 3-1
3.1 INTRODUCTION . 3-1
3.2 API PROXY . 3-1
3.3 API SERVICE ELEMENT . 3-27
3.4 SLE OPERATIONS . 3-52
3.5 SLE UTILITIES . 3-56
3.6 SLE APPLICATION . 3-64
3.7 HANDLING OF IN PROCESS THREADS AND EXTERNAL EVENTS . 3-71
4 STATE TABLES . 4-1
4.1 INTRODUCTION . 4-1
4.2 NOTATION . 4-1
4.3 GENERAL ERROR HANDLING CONVENTIONS . 4-2
4.4 STATE TABLE FOR ASSOCIATIONS . 4-2
4.5 STATE TABLES FOR SERVICE INSTANCES . 4-15
ANNEX A SPECIFICATION OF COMMON INTERFACES (NORMATIVE) . A-1
ANNEX B RESULT CODES (NORMATIVE) .B-1
ANNEX C STRUCTURE OF THE SERVICE INSTANCE IDENTIFIER FOR
VERSION 1 OF THE SLE SERVICES RAF, RCF, AND CLTU
(NORMATIVE) . C-1
ANNEX D SIMPLE COMPONENT MODEL (NORMATIVE). D-1
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CONTENTS (continued)
Section Page
ANNEX E CONFORMANCE (NORMATIVE) .E-1
ANNEX F INTERACTION OF COMPONENTS (INFORMATIVE) . F-1
ANNEX G INTERFACE CROSS REFERENCE (INFORMATIVE) . G-1
ANNEX H INDEX TO DEFINITIONS (INFORMATIVE) . H-1
ANNEX I ACRONYMS AND ABBREVIATIONS (INFORMATIVE) . I-1
ANNEX J INFORMATIVE REFERENCES (INFORMATIVE) . J-1
Figure
1-1 SLE Services and SLE API Documentation . 1-6
2-1 UML Stereotypes Used in This Recommended Practice. 2-3
2-2 Top Level Decomposition of the API . 2-7
2-3 Structure of the Package API Proxy . 2-9
2-4 Reporting and Tracing by the Proxy . 2-10
2-5 Configuration Database of the Proxy. 2-20
2-6 Structure of the Package API Service Element . 2-23
2-7 Reporting and Tracing by the Service Element . 2-24
2-8 Sequential Control Interface Component Class Controlled Component . 2-39
2-9 Concurrent Control Interface . 2-43
2-10 Structure of the Package SLE Application . 2-44
2-11 Reporting and Tracing Interfaces Provided by the Application . 2-45
2-12 Operation Objects . 2-49
2-13 Operation Object Interfaces for Common Association Management . 2-53
2-14 Common SLE Operation Objects . 2-54
2-15 SLE Utilities . 2-56
4-1 Processing Context for the Association State Table . 4-3
4-2 Processing Context for the Service Instance State Table . 4-16
B-1 Structure of Result Codes .B-1
F-1 Configuration of Components . F-3
F-2 Configuration of Interfaces for Service Provisioning . F-3
F-3 Interaction of API Components . F-4
F-4 Initialization and Shutdown . F-5
F-5 Collaboration Diagram for Use of Operation Objects . F-8
F-6 Sequence Diagram for Use of Operation Objects . F-9
F-7 User Side Binding (User Initiated Bind). F-12
F-8 User Side Unbinding (User Initiated Bind) . F-13
F-9 Provider Side Binding (User Initiated Bind) . F-14
F-10 Provider Side Unbinding (User Initiated Bind) . F-16
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ISO 18441:2016(E)
API FOR SLE TRANSFER SERVICES—CORE SPECIFICATION
CONTENTS (continued)
Table Page
C-1 Identifiers and Abbreviations for Attributes .C-3
E-1 Optional Features for the API Proxy . E-3
E-2 Optional Features for the API Service Element. E-6
E-3 Parameters That May Be Constrained by a Proxy . E-9
E-4 Parameters That May Be Constrained by a Service Element . E-10
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ISO 18441:2016(E)
API FOR SLE TRANSFER SERVICES—CORE SPECIFICATION
1 INTRODUCTION
1.1 PURPOSE OF THIS RECOMMENDED PRACTICE
The purpose of this Recommended Practice is to define a C++ Application Program Interface
(API) for CCSDS Space Link Extension (SLE) Transfer Services, which is independent of
any specific technology used for communications between an SLE service user and an SLE
service provider.
This API is intended for use by application programs implementing SLE services. It can be
configured to support SLE service user applications or SLE service provider applications.
This API is also intended to simplify the implementation of gateways that are required to
achieve interoperability between SLE service provider and SLE service user applications
using different communications technologies.
Using this Application Program Interface Recommended Practice, API implementations
(software packages) able to run on specific platforms can be developed. Once developed,
such a package can be supplied to new users of SLE services for integration with their user or
production facilities, thus minimizing their investment to buy into SLE support.
1.2 SCOPE
1.2.1 ITEMS COVERED BY THIS RECOMMENDED PRACTICE
This Recommended Practice defines the Application Program Interface in terms of:
a) the components that provide the services of the API;
b) the functionality provided by each of the components;
c) the interfaces provided by each of the components; and
d) the externally visible behavior associated with the interfaces exported by the components.
It does not specify:
a) individual implementations or products;
b) the internal design of the components; and
c) the technology used for communications.
This Recommended Practice defines those aspects of the Application Program Interface,
which are common for all SLE service types or for a subset of the SLE service types, e.g., all
return link services or all forward link services. It also defines a framework for specification
of service type-specific elements of the API. Service-specific aspects of the API are defined
by supplemental Recommended Practice documents for SLE return link services (references
[10], [11], and [12]) and SLE forward link services (references [13] and [14]).
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ISO 18441:2016(E)
API FOR SLE TRANSFER SERVICES—CORE SPECIFICATION
This Recommended Practice for the Application Program Interface responds to the
requirements imposed on such an API by the CCSDS SLE transfer service Recommended
Standards that were available when this Recommended Practice was released.
1.2.2 CONFORMANCE TO CCSDS RECOMMENDED STANDARDS
This version of the SLE API Recommended Practice conforms to the CCSDS Recommended
Standards for Space Link Extension Services, referenced in 1.7, with the exception of the
following optional features:
a) The negotiation procedure for version numbers in the BIND operation is not
supported. If the responder does not support the version number identified in the
BIND Invocation, it responds with a BIND Return containing a negative result and
the diagnostic ‘version number not supported’. The responder does not propose an
alternative version number.
b) Provider-initiated binding, specified by CCSDS Recommended Standards for return
link services is not included in this Recommended Practice. The management
parameters that specify the bind initiative are supported to simplify addition of this
procedure in later versions.
1.3 APPLICABILITY
The Application Program Interface specified in this document supports three generations of
SLE Transfer Service specifications, namely:
a) Generation 1 covering the services RAF, RCF, and FCLTU identified by the version
number 1 in the BIND operation, as specified by references [C1], [C2], and [C3];
b) Generation 2 covering
1) the services RAF, RCF, and FCLTU identified by the version number 2 in the
BIND operation, as specified by references [J9], [J10], and [J12];
2) the services ROCF and FSP identified by the version number 1 in the BIND
operation, as specified by references [J11] and [J13];
c) Generation 3 covering the services RAF, RCF, ROCF, FCLTU, and FSP identified by
the version number 4 in the BIND operation, as specified by references [4], [5], [6],
[7], and [8].
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ISO 18441:2016(E)
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Support for Generation 1 and Generation 2 of these services is included for backward
compatibility purposes for a limited time and may not be continued in future versions of this
specification. Support for Generation 1 (i.e., version 1 of the RAF, RCF and CLTU services)
implies that SLE API implementations of this specification are able to interoperate with peer
SLE systems that comply with the specification of the Transport Mapping Layer (TML) in
‘Specification of a SLE API Proxy for TCP/IP and ASN.1’, ESOC, SLES-SW-API-0002-TOS-
GCI, Issue 1.1, February 2001. For Generation 2 and 3 of these services, SLE API
implementations of this specification are able to interoperate with peer SLE systems that
comply with the specification of the Transport Mapping Layer (TML) in reference [9].
Provisions within this Recommended Practice that are specific for one or more generations
are marked as follows:
– [Gn:] for provisions specific to Generation n;
– [Gn,m:] for provisions specific to Generation n and Generation m.
Provisions that apply to all generations are not marked.
1.4 RATIONALE
This Recommended Practice describes the services provided by a software package
implementing the API to application software using the API. It specifies the mapping of the
SLE Transfer Services specifications to specific functions and parameters of the SLE API. It
also specifies the distribution of responsibility for specific functions between SLE API
software and application software. The distribution of responsibility has been defined with
due consideration for reusability of software packages implementing the SLE API.
The goal of this Recommended Practice is to create a guide for interoperability between
a) software packages implementing the SLE API; and
b) application software using the SLE API.
This interoperability guide also allows exchangeability of different products implementing
the SLE API, as long as they adhere to the interface specification of this Recommended
Practice.
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1.5 DOCUMENT STRUCTURE
1.5.1 OVERVIEW
This Recommended Practice is organized in two parts and a set of annexes.
1.5.1.1 Part I—The Descriptive Part
The descriptive part presents the API Model in section 2 using the Unified Modeling
Language (UML) (see reference [J6]).
1.5.1.2 Part II—The Prescriptive Part
The prescriptive part contains the specification of the API. In case of any discrepancies
between the descriptive part and the prescriptive part, the specifications in the latter shall
apply.
Section 3 contains detailed specifications of the API components and of the interfaces that
must be provided by the application.
Section 4 defines the state tables that must be implemented by the API.
1.5.1.3 Annexes
Annex A contains the detailed declaration of the C++ interfaces, which are common for all
SLE service types.
Annex B lists the result codes that are used by the API.
[G1:] For version 1 of the services RAF, RCF, and CLTU, annex C defines a standard ASCII
representation for the service instance identifier and lists the attribute identifiers and
abbreviations that are valid for the service instance identifier.
[G2,3:] For later versions of these services and all other services, these specifications are
provided by the applicable CCSDS Recommended Standards.
Annex D describes the design patterns and conventions that shall be applied to API
components. The specifications in this annex are also relevant for the application software
using the API.
Annex E defines requirements for software products claiming conformance with this
Recommended Practice.
Annex F describes the interaction of API components, showing several use cases.
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Annex G provides cross-references between interfaces provided by API components and
interfaces used by API components.
Annex H contains an index to definitions.
Annex I explains all acronyms used in this Recommended Practice.
Annex J lists informative reference documents.
1.5.2 DOCUMENTATION TREE FOR SLE SERVICES AND SLE API
This Recommended Practice is based on the cross support model defined in the SLE
Reference Model (reference [3]). The SLE services constitute one of the three types of Cross
Support Services:
a) Part 1: SLE Services;
b) Part 2: Ground Domain Services; and
c) Part 3: Ground Communications Services.
The SLE services are further divided into SLE Service Management and SLE Transfer
Services.
NOTE – In reference [3], SLE transfer services are identified; however, the complete
service specifications will be provided in separate Recommended Standards.
This Recommended Practice describes how the functions of an SLE transfer service provider
or user can be implemented in a software package for the purpose of providing or using one
or several SLE transfer services. It is part of a suite of documents specifying the API for
SLE transfer services:
a) Core Specification of the Application Program Interface for Transfer Services (this
Recommended Practice);
b) a set of Application Program Interfaces for specific Transfer Services; and
c) Internet Protocol for Transfer Services.
The basic organization of the SLE services and SLE API documentation is shown in
figure 1-1. The various documents are described in the following paragraphs.
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